[FFmpeg-user] A fix for "Automatic encoder selection failed"

[Mark Filipak]

The problem with this error notice: "Automatic encoder selection failed Default encoder for format 
mp4 (codec none) is probably disabled. Please choose an encoder manually.", aside from a missing 
period, is that it doesn't indicate the encoder that FFmpeg was looking for. In this script:

ffmpeg^
  -i "c:\8-bit ybr420 smpte170m vasc.mkv"^
  -map 0 -c:v libx264 -c:a copy -c:s copy^
  "c:\8-bit ybr420 smpte170m.mp4"

the encoder that is NOT found is NOT libx264. The encoder that is NOT found IS for subtitles and 
there's no '-c:s copy' switch. So FFmpeg searches for the default encoder for subtitles. Without 
looking at FFmpeg's source code, "Default encoder for format mp4 (codec none) is probably disabled" 
seems like nonsense.

Fix: Replace this:
"Automatic encoder selection failed"
by this:
"Automatic subtitle encoder selection failed".

The tip: "Default encoder for format mp4 (codec none) is probably disabled" is not needed. Certainly 
it is confusing.

--Mark.